The present invention is related to Japanese patent application No. 2000-68033, filed Mar. 13, 2000; the contents of which are incorporated herein by reference.
The present invention relates to an automatic headlight aiming device, and more particularly to an automatic headlight aiming device for a vehicle that automatically adjusts the direction of the optical axis of headlights mounted on a vehicle.
Presently, in a vehicle headlight, if the direction of the optical axis is directed upward when vehicle is inclined due to hills or other reasons, drivers of on-coming cars will be blinded. Or, if the direction of the optical axis is directed downward, the drivers"" visual recognition of distance is adversely affected. Therefore, there is a demand for keeping the optical axis of headlights in a fixed direction.
A result of computation of the inclination angle of the headlight optical axis with respect to the horizontal plane will sometimes vary with vehicle specifications. A situation is considered where only one vehicle height sensor, giving vehicle inclination information, detects vehicle height variation. Here, control constants vary with vehicle height sensor location. Specifically, sensors positioned on the front wheel side or rear wheel side of the driver""s or front passenger""s seat, may result in a different computed vehicle inclination angle and consequently in an improperly adjusted headlight optical axis direction.
To obviate such a drawback, it is necessary to use an ECU (electronic control unit) set to specific control constants conformable to the vehicle""s specifications. To meet this need, a plurality of ECU""s with different control constants are installed. However, since the ECUs have the same external appearance in spite of different product numbers, the wrong combination of the vehicle""s specifications and the ECU""s may be combined.
In addition, in the conventional device the optical headlight axis direction is controlled by changing the control constant according to a change in a vehicle occupants"" seating condition. If the control constant is frequently changed, the headlight optical axis direction will largely and unstably move the headlight optical axis.
Also, In JP-A-10-230777, using one vehicle height sensor and a seating sensor mounted on the front passenger""s seat, the vehicle inclination angle is estimated and the inclination angle of the headlights is changed. Since an ON/OFF signal from the seating sensor frequently varies with change in the occupant""s seating posture, the headlight aim will be frequently switched and unstably shifted according to the signal. Drives of other vehicles may mistake this for headlight flashing or a warning or a signal.
Therefore, the present invention provides an automatic headlight aiming device that properly adjusts the headlight optical axis direction with seating change by adopting common ECU""s despite a difference in vehicle specifications.
In a first aspect of the invention, the headlight optical axis inclination angle with respect to the horizontal plane is computed by an inclination angle computing means using inherent control constants according to inclination information detected by the inclination information detecting means. The control constants are set by the control constant setting means according to a specification discrimination signal which expresses a difference between various specifications of a vehicle. Thus the headlight optical axis direction is adjusted by the optical axis adjusting means based on the inclination angle.
In another aspect, the control constant is set by the control constant setting means, according to an evaluation signal, only once after vehicle installation. Therefore, the control constant once set in conformity to vehicle specifications will not improperly change due to noise or other reasons.
In another aspect of the invention, the headlight optical axis inclination with respect to the horizontal plane is computed by the inclination angle computing means based on an inclination information fed from the to inclination information detecting means. A vehicle occupant""s seating condition is detected by the seating condition detecting means. The response of the optical axis headlight adjustment by the optical axis adjusting means will change according to a result of seating condition detection or timing to start the optical axis adjustment will be delayed for a predetermined period of time. Therefore, it is possible to control a substantial change or unstable movement of the headlight optical axis direction if the vehicle occupants"" detected seating condition varies frequently.
In another aspect, the detection result is fed from the seating condition detecting means during a vehicle driving is fixed. Unstable adjustment or control of the headlight optical axis is prevented that is likely to occur when the seating condition detecting means is ignored.
Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are intended for purposes of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.